Evaluating 3D-printed bioseparation structures using multi-length scale tomography

X-ray computed tomography was applied in imaging 3D-printed gyroids used for bioseparation in order to visualize and characterize structures from the entire geometry down to individual nanopores. Methacrylate prints were fabricated with feature sizes of 500 mu m, 300 mu m, and 200 mu m, with the material phase exhibiting a porous substructure in all cases. Two X-ray scanners achieved pixel sizes from 5 mu m to 16 nm to produce digital representations of samples across multiple length scales as the basis for geometric analysis and flow simulation. At the gyroid scale, imaged samples were visually compared to the original computed-aided designs to analyze printing fidelity across all feature sizes. An individual 500 mu m feature, part of the overall gyroid structure, was compared and overlaid between design and imaged volumes, identifying individual printed layers. Internal subvolumes of all feature sizes were segmented into material and void phases for permeable flow analysis. Small pieces of 3D-printed material were optimized for nanotomographic imaging at a pixel size of 63 nm, with all three gyroid samples exhibiting similar geometric characteristics when measured. An average porosity of 45% was obtained that was within the expected design range, and a tortuosity factor of 2.52 was measured. Applying a voidage network map enabled the size, location, and connectivity of pores to be identified, obtaining an average pore size of 793 nm. Using Avizo XLAB at a bulk diffusivity of 7.00 x10(-11)m(2)s(-1) resulted in a simulated material diffusivity of 2.17 x 10(-11)m(2)s(-1) +/- 0.16 x 10(-11)m(2)s(-1).

Automated summary

This study applied X-ray computed tomography to image and characterize 3D-printed gyroids for bioseparation. It visualized structures from the overall geometry down to individual nanopores and achieved digital representations across multiple length scales for geometric analysis and flow simulation. Comparisons between the imaged samples and the original designs were made to analyze printing fidelity, and parameters such as porosity, tortuosity factor, and pore size were measured.